The present invention relates to new esters of the 21-thiol steroids having the general formula given at (I) below ##STR2## in which: R.sub.1 represents an alkyl radical comprising a number of carbon comprised between 4 and 9 atoms of carbon, or the parafluoro-phenyl radical;
R.sub.2 represents hydroxyl or the ketone function. PA1 The 21-thio-acetate and 21-thio propionate of prednisolone (U.S. Pat. No. 2,814,632) have been described as possessing an adreno-corticoid activity accompanied by considerable diuretic activity. PA1 The 21-thio-acetate of dexamethasone (French Pat. No. 1187 M) has been proposed as an anti-inflammatory product with a local action and a systemic action. PA1 Cutaneous illnesses and mucous illnesses that can be treated by corticoids; PA1 Auto-rhino-laryngological and opthalmological illnesses of an inflammatory and/or allergic nature; PA1 Low digestive inflammations such as colities, recto-colities, and and recto-sigmoiditis; PA1 Collagen troubles, articular and rhumatismal illnesses; PA1 Asthma, emphysema and respiratory fibrosis.
Several publications describe the modification of the group 21-hydroxy-methyl of the corticoids, and more particularly the replacement of the oxygen of this function by sulphur.
Thus, the 21-thio-acetate of hydrocortisone is synthetized and declared free of any interesting biological activity (J. Org. Chem. 26,1223, 1961).
Other derivatives have been proposed as anti-inflammatory products having solely a systemic action on the system or a local action and a systemic action:
The therapeutic use of corticoids having a systemic action generally gives rise to harmful "secondary effects" (Presse Medicale No. 31,1419-1423, 1970).
These secondary effects comprise mainly: endocrine troubles, sodium retention accompanied by a leakage of potassium, weakening of the defense reactions of the organism, which result in a pro-infection effect, digestive ulcers and disturbances of the glucidic, proteic and lipidic metabolisms.
The number and the variety of these secondary effects necessitate a certain prudence and careful supervision during the use of these products.
The present invention has for its object to find a remedy for these disadvantages.